I would like to split a string on whitespace that has 4 elements:
1 1 4.57 0.83
and I am trying to convert into List[(String,String,Point)] such that first two splits are first two elements in the list and the last two is Point. I am doing the following but it doesn't seem to work:
Source.fromFile(filename).getLines.map(string => {
val split = string.split(" ")
(split(0), split(1), split(2))
}).map{t => List(t._1, t._2, t._3)}.toIterator
How about this:
scala> case class Point(x: Double, y: Double)
defined class Point
scala> s43.split("\\s+") match { case Array(i, j, x, y) => (i.toInt, j.toInt, Point(x.toDouble, y.toDouble)) }
res00: (Int, Int, Point) = (1,1,Point(4.57,0.83))
You could use pattern matching to extract what you need from the array:
case class Point(pts: Seq[Double])
val lines = List("1 1 4.34 2.34")
val coords = lines.collect(_.split("\\s+") match {
case Array(s1, s2, points @ _*) => (s1, s2, Point(points.map(_.toDouble)))
})
collect "Builds a new collection by applying a partial function to all elements of this list on which the function is defined.". It's just like map but leaves only the elements in the domain of the partial functionYou are not converting the third and fourth tokens into a Point, nor are you converting the lines into a List. Also, you are not rendering each element as a Tuple3, but as a List.
The following should be more in line with what you are looking for.
case class Point(x: Double, y: Double) // Simple point class
Source.fromFile(filename).getLines.map(line => {
val tokens = line.split("""\s+""") // Use a regex to avoid empty tokens
(tokens(0), tokens(1), Point(tokens(2).toDouble, tokens(3).toDouble))
}).toList // Convert from an Iterator to List
case class Point(pts: Seq[Double])
val lines = "1 1 4.34 2.34"
val splitLines = lines.split("\\s+") match {
case Array(s1, s2, points @ _*) => (s1, s2, Point(points.map(_.toDouble)))
}
And for the curious, the @ in pattern matching binds a variable to the pattern, so points @ _* is binding the variable points to the pattern *_ And *_ matches the rest of the array, so points ends up being a Seq[String].
There are ways to convert a Tuple to List or Seq, One way is
scala> (1,2,3).productIterator.toList
res12: List[Any] = List(1, 2, 3)
But as you can see that the return type is Any and NOT an INTEGER
For converting into different types you use Hlist of https://github.com/milessabin/shapeless
